Setting timing on Non-points bike

[Tombo]

Hey guys -

Just got a 1980 XS400 Special, and I have noticed the bike sometimes runs on one cylinder (the left one) while idling. From research, it seems like I need to have valves adjusted, timing adjusted, and finally (and probably most importantly) I need to make sure the carbs are clean.


I know I have spark (after adjusting carbs, I attached my color tune - which is how I found out the right cylinder only fires with more throttle).

I still need to adjust valves (I need to buy angled feelers), and I have all I need to do my carb rebuild - but I want to eliminate timing as an issue before I dive deep into the carbs.

So my question - on this non-points bike, how is my timing adjusting different? Or better yet, is there a "how to" on this I haven't found with research?

 

[drewpy]

if you want to test your timing, Use a strobe lamp!

take off the left cover and point the gun at the little window. the light "freezes" at the point where it should fire and you should quickly find out is it's out.

if you havn't got one, they are cheap to buy or borrow one

 

[Tombo]

Is there a way to do it without that tool? I have a manual, but it seems to rely on the points for the actual adjustment - and since I don't have points to adjust, What technique do I use?

 

[drewpy]

Is there a way to do it without that tool? I have a manual, but it seems to rely on the points for the actual adjustment - and since I don't have points to adjust, What technique do I use?

not really, once electronic ignition is set then it stays there anyway!

 

[Tombo]

So I rotate the whole ignition unit to "adjust" the timing as I would the points unit as discussed in the manual? And I MUST use a stroboscope to find whether it's in sync or not? What does the stroboscope attach to?

And with the principal that the ignition is non-adjustable, would it be reasonable to assume that since I'm getting one cylinder firing, that the other cylinder SHOULD be firing too? (and that I'm barking up the wrong tree....)

 

[drewpy]

there is a very small amount of adjustment for each side.

the strobe use the pulse from the HT lead to fire its light. switch HT leads to check the other side.

If you can borrow one it would be better as it literally takes 5 seconds to check with the cover off.

 

[Tombo]

Drewpy - would this do? Cheapest I can find

http://www.oreillyauto.com/site/c/d..._3137&keyword=timing+light&pt=N0665&ppt=C0103

 

[drewpy]

doesn't say if its a xenon as they give out a nice white light.

will do the job, i got mine for £20 off ebay!

 

[Tombo]

Drewps - I got my timing light and adjusted so the line totally lines up.

Is this correct?? I've noticed some "rocking" or hesitation while holding speeds at about 4-5k rpm. I have changed to the jbm diaphragms, and I feel like all in all it's running better - but I've been wondering if I should have adjusted timing so that it fires a touch BEFORE the line? Or if I should adjust for an rpm increase or decrease?

I have a few carb parts I want to replace coming in, so I will do another blow-out with yee olde compressor before reasembly, see if we can't see a difference. I also intend to replace the exhaust with replacement s mine came with a blued out, broken baffle, and *crack* in the left side muffler. Perhaps this will sort it out
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After that - perhaps I need to lift the needle?

 

[drewpy]

the line you mean the firing line on the stator?

keep the revs low as the advance will kick in and affect the timing.

looks like your on the right lines though. did you check both sides too?

are you running standard airfilter and exhaust?

 

[Tombo]

"the line you mean the firing line on the stator?

keep the revs low as the advance will kick in and affect the timing.

looks like your on the right lines though. did you check both sides too?

are you running standard airfilter and exhaust?"

Yes - using the timing light, the "notch" on the timing window lines up perfectly with the timing line

My revs are idle during adjustment, probably 1.2k - but my question about revs - the timing will effect this in some manner, will it not (as in, they will increase or decrease depending)?

It's been almost a month since I made the adjustment, but if I remember correctly, the revs went up when I adjust it correctly, to the point that I had to just about "turn off" the idle adjustment screw to get a reasonable idle. (meaning I had to turn it to the left before the screw was no longer contacting the throttle)

I did not attach the right side plug wire to my light, because I don't think I have any adjustment on this do I? Based on the mechanism for adjustment, wouldn't I be automatically adjusting the right side if I've adjusted the left side?

I am running stock airfilters and exhaust.

Because you are the true undeniable expert on here, I was just prodding your brain. My question is more procedural, because I lack the experience (this is my first timing light, first timing adjustment, etc!) For adjusting timing with strobe, should the timing line align directly with the "notch" in the window? Or should it be slightly in front? slightly behind?

I can remember making the timing adjustment - it seems like it made a positive change in my bike. Currently the bike actually runs well - good power when you gun it, strong idle that is NOT irratic.... But as I had said - it feels sometimes like it hesitates a little, or "rocks" when you are just maintaining speed (but seems to accelerate smoothly, has lots of power that takes me past what the needle will read). However, it doesn't seem right, regardless of my lack of expertise

I also feel that the bike is running hot - but I would have no way to tell, aside from the plugs - which seem to be ok, but they do look a bit lean (a little whiter than I'd like). However, none of the typical symptoms of a lean mixture are present, aside from the "hesitation" and "rocking" in the 1/4-3/4 throttle area.

 

[drewpy]

there are two adjustments in the trigger mech.

one is the module its self and the other is the plate. this moves both so your to-ing and fro-ing all the time